Process and apparatus for generating steam



Dec. 31, 1940. I w. KERRICK PROCESS AND APPARATUS FOR GENERATING STEAMFiled March 6. 1959 LOAD F OM TANK Kw CF. I? R emw mxw M m W a m w mm?m2 5Hv Wm G 5 FOP THE FIRM Patented 1... at, 1940 PATENT OFFICE PROCESSAND APPARATUS FOR. GENERATING STEAM Walter B. Kerrick, Los Angeles,Calii'., assignor to Clayton Manufacturing Company, Alhambra, CaliL, acorporation of California Application March 6, 1939, Serial No. 259,956

Claims.

My invention relates to the generation of steam and is believed to benovel both in its process steps and in the novel combinations oielements used in the structure.

In general, the invention comprehends pumping into a heating zone anamount or water greater than that required to. meet the steam demand,heating the water to a steam-forming temperature at which some steamwill flash therefrom when the pressure is reduced or'at which some steamis formed in the heating zone. avoiding the application of any suchamount of heat as would vaporize the entire stream, separating steamfrom the excess unvaporized water in a steam chamber, and circulatingwater from the steam chamber to the intake of the heating zone.Preterably, the heating zone comprises an elongated passage so designedwith reference to the amount of waterdelivered thereto that ,any steamformed therein will be kept uniformly mixed with the water as long asthe flow con It is an object of the present invention to provide asteam-generating process and apparatus in which ebullition conditionsare ideal, and in which the steam is produced substantially free ofentrained minerals, even though the size of the steam-producing unit issmall. This may be accomplished by jetting the heated stream into theupper end of the steam chamber in such manner as to iorm myriads 01small water droplets which enormously increase the area of water incontact withthe steam. x 7

It is another object of the present invention to provide a novel processand apparatus for controlling the amount of water in the steam chamher.v

A further object is to withdraw water from the steam chamber and addmake-up water theretoat reducedpressure, after which the combined wateris pumped into the system for circulation therethrough. l

Another object of the invention is to withdraw all water from the steamchamber tending to rise above a predetermined position which representsthe maximum desired position of the surface of the body of watertherein.

Another object of the invention is to conduct the water thus withdrawnto a tank or chamber and add make-up .water-tothis chamber in controlledamount.

' p The load may be of such type as to condense all or a portion of thesteam. thus making available condensate iorreturn to the heating system,and it is an object 01' the invention to return all or a portion of suchcondensate in heat-transfer ring relationship with the water withdrawnfrom such condensate to'a second chamber which receives at least aportion of the excess water reaching the steam chamber.

Another object of the invention is to provide a heat transier betweenthe excess water circulated through the system and the make-up'wateradded thereto.

the steam chamber and, preferably, to return Certain of the controlfeatures of the invention 10 are also believed to be novel in themselvesor in combination with other elements 01' the invention. For example, itis an object of the present invention to control the addition or make-upwater in 15 such manner that the water thus added is saidcient, over aperiod 01 time, to meet the steam demand, and another object resides inthe supply of the make-up water to a second chamber separate from thesteam chamber to maintain a substantially constant amount of water inthe former.

. Another object of the invention is to provide a steam-generatingsystem in which the pumping action can be controlled automatically toprevent wastage oi heat during idling periods or periods of low steamdemand.

Another object of the invention is to provide a steam-generating systemin which the thermal conditions of the stream discharged into the steamchamber can be maintained through con trol of the heat, and in which anyreduction in pumping action will be automatically compensated by areduction in the amount of heat transmitted to the stream.

Another object of the inventionis to provide a steam-generating systemin which local overheating is prevented durlng continued operation andin which scale formation on the walls of the heating zone issubstantially eliminated, thus insuring long life of equipment andconstancy of operating conditions.

' Further objects .and advantages of the invenload, and also indicates amodified pumping arrrangement particularly adapted to this alternativesystem.

Referring particularly to Figure 1', the apparatus, in general, includesa pump means IQ for iorcing water'through a heater ll provided with aheat-control means 12 and discharging a heated stream into anaccumulator or closed container' l3. Steam is withdrawn from the upperend thereof and supplied to a load 44', The excess water collecting inthe accumulator i2, together ing pump 20 and a feed water pump 2|,respecwith necessary make-up water, is fed to the pump means ill forreturn to the heater II. A tank I5 is provided to receive at least aportion of this excess waterand the make-up water can be added theretoIrom any water supply, indicated as a pipe I8.

In the embodiment shown in Figure 1,. the pump means III is shown asincluding two pumps respectively termed, for convenience, acirculattivelywithdrawing water from the accumulator l3 through a pipe22 and from the tank l5" heater or subsequent equipment. Check valves 24and 25 are provided to prevent'any reverse flow and, if desired, may beformed as a part of the pumps 20 and M. The streams respectivelydelivered by the pumps 20 and 2| combine at a junction 21 disposed in apipe 28 which delivers the combined water to the heater II. It will beclear, however, that the streams withdrawn from the accumulator I3 andtank l5 may be combined in various manners with regard to the pump meansemployed and need not come together on the discharge side. It will beclear, likewise, that the capacities of the pumps 20 and 2| need not beequal, and various expedients can be used for determining. the relativeamounts of water pumped by these pumps. If displacement pumps are used,they can be of the double acting orsingle acting type, though the formeris preferred. As shown in Figure 1, thes pumps are driven by a commondrive means indicated as an electric motor 29, but it should beclearthat independent drives for' these pumps can be used, ashereinafter shown, and that-the interconnecting mechanism between thedrive and the pumps can be of any desired type. For illustrative purpses, a Scotch yoke means 30 is shown in this connection.

The function of the heater II is to heat the stream of water deliveredthereto from the pump means Ill to a steam-forming temperature, By thisterm, I have reference to such temperature as will permit steam to formeither in the heater itself or in the accumulator l3, or in both. Thepreferred mode of operation contemplates the generation of some steam inthe heater l I while distinctly avoiding any such heating as wouldvaporize the entire stream. In this'mode of op,- eration, it is verydesirable to maintain any steam generated in the heater II in intimatemixed relation with the water and to avoid any separation of such steamas might form steam pockets or slugs of steam in the discharge. Thesefunctions can be performed by the type of heater shown.

This heater II is shown as including a housing 33 in which is disposed atubular unit, shown as being in the form of a coil 34, and whichprovides an elongated heating zone communicating with the pipe.28. Theuse of pancake coils will be found desirable in this respect and, inthe' event of heating by products of combustion, it is be used withoutdeparting from the spirit of the invention, a burner is diagrammaticallyshown in this regard and receives fuel through a pipe stancy ofoperation under varying steam demands and correlation between the heatsupplied to the stream and the amount of water delivered to the heater,I provide a heat-control means 12 of any suitable type responsive tothethermal condition oi th stream adjacent the discharge end of theelongated heating zone and operatively connected to the valve 31. Thedetails of the particularlydescribed heat-control vmeans are not, perse, a part of the present invention but the means i2 is novel in thecombination hereinafter described. The constructional details of thisheatcontrol means are shown in my Patent No. 1,968,525. Suflice it tosay that the heated stream discharging from the tubular unit 34 enters apassage of a head member 4| which communicates with an inner pipe 42disposed within an outer pipe 43 so. that the stream moves leitwardthrough the inner pipe 42 and then reverses its direction of movement,with resulting turl bulence, and moves rightward through an annularspace between the inner and outer pipes 42 and 43 to return to the head4| and be discharged through a pipe 44. It is usually advantageous touse an inner pipe 42 ofslightly smaller internal diameter than the pipecomprising the tubular unit 34 whereby some throttling action isobtained and the stream is permitted to expand while moving along theinner pipe 42 or after discharge therefrom. The outer pipe 43 is formedof a material having good heat conductivity properties and is disposedclose to the burner 35 so as to be directly under the influence of theflame. The left end of thisouter pipe 43 is operatively connected to thevalve means 31 in such manner that the amount of fuel passing throughthis valve means increases and decreases in response respectively to acontraction or expansion of the outer pipe 43, as disclosed in my patentsupra.

correspondingly, the amount of heat supplied to the tubular unit 34 inthisembodiment of the invention iscontrolled in response to thetemperature, and thus the "expansion and contraction with changes intemperature, of the outer pipe 43. It will be clear that this outer pipereceives heat from the burner and acts to transmit heat to the annularstream moving therethrough.

This being the case, the outer pipe 44 tends to be heated by the burnerand cooled by the stream, and this pipe is thus at a'temperature 7absorbed from the burner, the rate of heat trans-.

mission through the outer pipe, etc., but, primariiy, the temperature ofthis pipe is dependent upon the rateat which heat is taken therefrom bythe stream." This, in turn, depends upon 1 the-amount or steam presentin this stream.

-The presence of material amountsyof steam in the annular streamdecreases the heat transmission fromthe pipe to thestream and, ineflect, this device can be made to operate as a steamproportioncontroller to maintain substantially constant the proportionof steampresent in the stream so long as the pressure remains substantiallyconstant. It thus differs from an ordinary thermostat. :As described inmy patent supra, an adjustment means 46 controls the position ofthe headll relative to the valve means if so that, by turning this adjustmentmeans,

the proportion of steam present in the outgoing stream can be changed toa new value, after which the heat-control means will maintain this valuesubstantially constant so long as the pressure in the heat-control meansremains substantially constant. v

While a particularly advantageousheat-control means has. been shown inFigure, ;1, it should be clear that the invention is not limitedthereto, Other heat -control means can be used in place of theparticular means shown. In some .instances, no automatic heat-controlmeans need released into the accumulator l3 though, in some instances,the throttling action can be small or negligible, if desired. As shown,this nozzle is .oi the multi-orifice type, the combinedareas of theorifices being somewhat less than the area of the opening provided bythe pipe 44.

The functioniof the accumulator I3 is. primarily to separate the steamand the water, whether this steam was formed partially ahead of, thenozzle 49 or'by hashing in the accumulator l3. This accumulatorprovidesa steam chamber 50 bounded by a closed container 5l ,capabie ofwithstanding pressure; In the lower end of the steam chamber, a body ofwater 52 collects and the upper portion ot this steam chamber com prisesa steam zone into which the nozzle 46 discharges.

By permitting the stream to ex- "pand upon dischargeinto the steamchamber,

or by use of other expedie'nts, the unvaporized liquid in the stream issuddenly broken up into I very small droplets, thus greatly increasingthe area of contact between the steam and the water and thusfacilitating liberation of the steam and providing such eflicientebullitlon that the steam withdrawn to meet the demand has a negligiblemineral content, often not more than two or three parts per million. Theexcess unvaporiz'ed water moves downward in the steam zone to formand'maintain the bodyot water 52. and carries with it the mineralspresent in the water used for meeting the steam demand, these mineralsbeing largely deposited in the lower end of the container 5| from whichthey can' be periodically withdrawn through {a blow-oi! 53. This body ofwater is maintained at the temperature corresponding to the boilingpoint at the pressure existing in the steam chamber. and is availablefor generation of steam should this pressure be lowered, asby suddenincrease in steam demand.

Steam is withdrawn from the upper end of the steam chamber 56 by anysuitable means. One advantageous wayof withdrawing the steam is througha conduit 54 disposed concentric with respect to the downward-extendingportion of the pipe 44, this conduit forming a part of an elbow 55 fromwhence the steam moves through a pipe 56 to the load It. Any desiredthrottle means may be used to regulate this discharge of steam.Diagrammatically, a valve 51 is shown in this capacity.

The surface of the body of water 52 is indicated by the numerol 66, andit is very desirable to maintain this surface below a predeterminedmaximum position/to determine the minimum volume of the steam zonethereabove and thus insure the desired ebullitlon and maintain thedesired operating conditions. This result'is accomplished in the presentinvention by a means for withdrawing from the steam chamber 56 any watertending to raise the surface 66 above a predetermined maximum position,which is ap-' zontally adjacent the uppermost position of the surface 66so that any water tending to rise above this entry portion will bedischarged through the pipe means 62. A steam trap 65 is provided inthis pipe means and serves the function of allowing water to bedischarged while preventing any discharge of steam. This steam trap maybe of conventional design, for example, of the type including a floatwhich opens a valve discharging into a pipe 66 when the water in thesteam trap rises to lift the float. Correspondingly, when the surface 66is below the entry portion 63, no steam will be discharged into the pipe66 but any rise of this surface will permit into the pipe 66 todetermine the uppermost position of the surface 60. If desired, thepressure .in the pipe 66 may be considerably lower than that in the pipemeans 62 so that, after movement through the valve of the steam trap,some heat transfer is effected between the material of the streampassing through the pipe 66 and a body of water." maintained in thistank l6.

Various methods of thus transferring heat can be used without departingfrom the spirit of the invention. The pipe 66 is shown as extendingdownward into the body of water; 66 and the water flowing in this pipemay be discharged directly into the body of water, or it can bedischarged at a higher elevation and move downward into the body'ofwater. If desired, an inof the water from the. body 66 into the sleeveto give a desirable mixing action. with consequent very eiiicient heattransfer. In addition,

the pipe 66 is shown as including a coil II disposedin the body of waterso that a heat transfer takes place even before discharge from thenozzle 89. It will be clear that either or both of these systems can beused to transfer heat to the body of water 6| and thus. avoid heat Thetank It is shown as including a vent 12 equipped with a valve 13. If itis desired that the pressure in the tank l5 should be substantiallyvatmospheric, this valve 12 can be opened-or an open-top tank can beused. on the otherhand. it is within the-contemplation of the presentinvention to maintain a superatmospheric pressure in the tank I5 duringnormal operation, or to permit wide pressure variations therein, inwhich event the valve ll may be closed. In the event that the pipe 18communicates with a domestic water supply, it is usually desirable toopen the valve 13 and maintain atmospheric pressure in the tank It.

If desired, all or a portion of the condensate from the load it can bereturned to the tank I! through a pipe 14. If all of the steam iscondensed, the pipe ll will return to the tank Ii an amount of watercorresponding to that required to meet the steam demand, and no make-upwater will be added to the system except as re-, quired to compensatefor any leakage-in the system. i It it usually desirable to dkpose asteam trap 15 in the pipe 14' so that only. is delivered to the tank It.This steam trap may be of the type previously described. or may be of atype whichadditionally cools the stream so as to insure thatnosubstantial amount of steam will be delivered to the tank I! andwasted if this tank is open to the atmosphere. Onthe other hand, variousmeans can be used for returning condensate from the load it to the tankIS without departing from the spirit of the invention. One suchpossibility isshown in Figure 3 in which the condensate is combined withthe excess liquid drawn from the steam chamber before discharge into thetank i5.

It is desirable to add to the tank i| an amount of make-upwatersufllcient to meet the steam demand. In the event 0 use of thecondensate return pipe H, the a cunt of make-up-water delivered by thepipe It need be only sumcient to compensate for any steam not condensed.The load It often is of such character as not to make availablecondensate from the entire amount of steam delivered thereto, in. whichevent make-up water is addedthrough the pipe ii to compensate for this.A convenient and very satisfactory way of controllingthe makeup watersupplied through the pipe N 'is' to us e a valve ll controlled by afloat II and acting in such manner as to maintain the surface of thebody of water 6| substantially constant, this surface being indicated bythe numeral 1|. Thus.

when this surface drops, the float 1| will lower to permit make-up waterto enter through the valve 'II until the surface 1| is raised; to thedesired point.

The invention comprehends the use of a re circulation means forreturning to the heater any" excess water, not used for supplying thedemand, and which is delivered to the steam chamber of the accumulatorl3. As will be explained with reference to Figure 3, all of this excesswater may move through the pipe means 62 but, in the form oftheinvention shown in Figure l, excess water can move from the steamchamlfir either through this pipe means G2 or through the pipe 22 whichopens on the lower portion of the body-9f waterq|2 and communicates withthe intake ofthe pump 2|. This pump 2|, if of the constantdisplacement'type. can thus withdraw from; the steam chamber asubstantially constant amount of the excess water. "Ihe'capacity of thepump 2| is preferably such that it will not withdraw all of theexcess-water, the pipe means |2 being relied upon in this connection sothat the-surface will -never rise above the entry portion it As will be"clear from 'Figure 1, the pipe 23 communicating with the intake of thepump 2! is in open com-' munication with the body of water is in thesecheata-con'trol means l2 will supply an appropriate amount'of heat tomeet the steam demand, and the amount of make-uplwater added to thesystem will be automatically controlled. However,. in the event that thethrottle 51 is closed, or in the event of very low steam demands, someheat losses will take place if the pumps are driven continuously as hebody of liquid 8| in the second chamber 1 may reach the boiling point atthe presure existing therein. Under such conditions of .intermittentsupply of steam or wide variations in steam demand to a point wherepractically no steam is desired at a particular time, I prefer tocontrol the pumping action--in such manner that the supply of water tothe heater Ii will be reduced until such time as the '40 steam demandincreases, the heat being controlled so as to prevent overheating.Various means can be used in this connection without departing from thespirit of the invention, but

I find it very satisfactory to start and stop the motor 2| in responseto thermodynamic conditions in some portion of the system, for examplein the chamber ll of the accumulator I3. As shown, a pressure switch Nis used in this con: nection and includes a diaphragm 8| with a linkageconnecting this diaphragm with a switch when the pressure in the steamchamber SI .of the accumulator it rises above a predetermined value,determined by the setting of the pressure switch 25, the switch .88opens to de-' energize the motor 2|. When the pressure in this steamchamber drops below a predetermined value, determined again by thesetting of the pressure switch the switchwill again close to start themotor 2|. It will be clear, however, that the pressure switch 85, whiledescribed with reference to operation under changes in pressure, willoperate likewise with changes in temperature in the steam chamber astemperature and pressure conditions therein are, of course. correlateddue to the fact that the temperature is at the boiling point of water atthe pressure existing. Correspondingly,--the means responsive topressure variations includes, likewise, a means actuateddirectly bytemperature changes, and the term is not used with reference only toapressure-operated switch.

In Figure 1,.the motor 2| is energized from a line including a masterswitch 9|, -and the switch II is connected inseries with a solenoidpumps.

winding 92 across the line 90 beyond this master switch. An armature911s connected to a switch arate drives therefor and, if desired, tostop the pumping action of only one of the pumps in response to changesin pressure or temperature in the steam chamber 50 of the accumulatorI3. ,In this connection, it is possible to actuate the pumpzilcontinuously and to start and stop the pump 21 in response to changesin pressure or temperature in the steam chamber 50, the heat beingappropriately controlled at all times, whether by manual or automaticmeans.

Figure 2 shows this manner of controlling the Here, a branch line 96conducts current from the line 90 at a point beyond the master switch toa motor 91 which drives the pump 20. A separate motor "is used to drivethe'pump II and this motor is connected in circuit with the switch-94actuated as previously described. Also, in Figure 2, the pumps 20 and Hare diagrammatically shown as being of the centrifugal type for it willbe clear that it is not always imperative to use pumps of thedisplacement type.

The preferred mode of operation of the device shown in Figure 1 is asfollows. The pumps 20 and 2| serve ,to deliver a substantially constantamount of water to the heater ll, irrespective of the pressure built uptherein due to friction in the tubular unit 34, the heat-control meansi2, or the nozzle 49, so long as these pumps remain in operation.correspondingly, there is set up a column of liquid which isprogressively heated to a steam-forming temperature under the control ofthe heat-control nieans i2. During the time that this stream is heated,it is moving through the elongated heating zone of the tubular unit 34.

'In the preferred mode of operation, and while the'steam demand islarge, sufiicient heat is applied so as to generate so e steam in thelower turns of the ,tubular unt 34. It is important;

I however, that any steam generated therein should i ever, conditions ofturbulence are maintained so be maintained uniformly dispersed in thewater,

thus avoiding the formation of steam pockets,

scaling of the elongated heating zone, and nonuniform quality of thestream moving'through the pipe 44. If steam is generated inthe tubularunit 34, it will. be apparent'that the volume of the stream increasesvery materially, with consequent increase in velocity and friction, thusdeveloping a higher friction head against which the pumps 20 and 2| mustoperate.

Under other conditions of operation, it is not 'essential to form steamin the lower portion of the tubular unit 34, in which event the devicecan be used .to deliver a stream of superheated water to the nozzle 48,or astream of superheated water to the annular passage of theheat-control means I! where, by expansion from the inner pipe 42 or byheat transferred to the annular stream, some steam may be generated.Even then,'howas to prevent formation of steam pockets or slugs of steamin the stream delivered to the nozzl 49. Regardless of whether steam hasbeen formed ahead of the nozzle 48, the stream delivered thereto willcontain superheated water. When the pressure thereon is reduced (as itmust be when moving through the nozzle 49), a portion present inventioncontemplates such control of the heating and pumping actions as willprevent vaporization of all of the water supplied to the heater ll sothat a substantial portion of'the water pumped into the heater willcomprise an excess not required to meet the steam demand.

of this water'will ilash into steam. However, the I This excess waterincreases the velocity in the tubular unit 34, decreases any scalingtherein, and

makes available an automatic control of the entire system throughre-circulation.

The excess unvaporized water accumulates in the steam chamber in theform of the body of water 52 and a portion thereof is returned to thepump 20 through the pipe 22. All water tending to raise the surface illabove the entry portion 63 moves through thepipe means 62 and to thesecond chamber 61. The preferred mode of operation involves the,maintenance of a somewhat' lower pressure in the second chamber 61 thanin the steam chamber 50 of the accumulator It. This permits adding ofmake-up water, either from an outside source or from the condensate fromthe load, at a lower pressure than that which exists in the steam'-chamber. Heat is transferred between the streams entering the sec- 0ndchamber throughtlie pipes 66,14, and I6,

and the resulting water is withdrawn through the pipe '23 to the pump 2|and is then blended at the junction 21 with the-warmer water deliveredby the pump III.

In Figure 1, when the steam demand is reduced, as by partially closingthe valve 51, the pressure in the steam. chamber 50 of the accumulatorl3 may rise suificiently to actuate the pressure switch 85 and thus stopthe pumping action of both pumps. The heat-control means II will operatealmost immediately due to the fact that the cooling stream does notcontinue to flow through the annular passage between the inner and outerpipes 42 and 43, thus raising the average temperature of the latter anddecreasing the fuel supply. It a small amount of steamis withdrawn fromthe steam chamber through the throttle at this time, the pressure willgradually reduce and steam can be liberated from the body of water 52 inan amount corresponding to the reduction in pressure. -When th pressurehas, dropped to a predetermined point, the pressure switch 85 will closeto start the pumps, and the outer pipe 43 of the heat-control means willbe cooled by the stream so that the burner will come into operationimmediately and will supply an amount of heat required to maintainsubstantially constant the thermal conditions of the' stream dischargedinto the pipe 44.

During normal operation of the device shown in Figure 1, any largeincrease in steam, demand will lower the pressure in the steam chamberslightly, thus increasing the amount of steam formed by flashing orgenerated from the body of water 52. The amount of excess unvaporizedwater will thus decrease and, even though the pump 20 is withdrawing aconstant amount of water from the steam chamber, a smaller amount ofwater will move through thepipe means 62 to the second chamber 61 of thetank I 5. The pump 2 I is, of course, drawing water from the tank It andany reduction in the amount of wa ter delivered thereto through the pipe66 and not compensated for immediately by an increase in condensatethrough the pipe 14 will be reflected in a lowering of the float I8 topermit a larger amount of make-up water to enter the second chamber 61through the pipe l6. Correspondingly. the amount of make-up water, willbe automatically increased to meet the steam demand.

Should the throttle be entirely closed, the excess water enteringthesteam chamber will be withdrawn partially through the pipe 22 andpartially through the pipe means 62, and the amount of water moving intothe second chamber 61 through the pipe means 62 will be suflicient tomaintain-the float I8 in such position. that no make-up water will berequired except to come pensate for any possible leakage. This will bethe mode of operation before the pressure switch opens the circuit tostop the pumping, or

if this pressure switch is eliminated from the system, as it can be inmany installations.

correspondingly, the feature of by-passing from the steam chamber anyexcess water tending to raise the surface 60 above a predeterminedmaximum is very desirable. It acts not only to prevent an excess amountof water in the steam chamber but also functions to permit addition ofmake-up water in amount required to meet the steam demand by a verysimple means. 1

The mode of operation of the system shown in Figure 2 is substantiallythe same as that described with reference to Figure 1 except that, whenthe pressure in the steam chamber rises above a predetermined point,only the feed water pump 2| is rendered inoperative by the opening ofthe pressure switch 85. In this instance, no excess water will beintroduced into the system from the chamber 61, but water will bewithdrawn from the body 52 in the steam chamber by the circulating pump20 and will continue to be circulated through the system so long.as the.switch 9| remains closed. The advantage of this arrangement is a savingin the B. t. u. of the latent heat of the water that would otherwise belost in any excess water that moved through the pipe means 62 to thechamber 61. In effect, this system cuts out the supply of feed andmake-up water during the time that the pump 2| is shut off and providesfor repeated circulation of the water already in the system by means ofthe circul ating pump 20. However; it will be clear that, even if areduced amount of water is forced into the heater, the heat-controlmeans l2 will reduce the fuel to such an extent that substantially thesame thermal conditions will be maintained in the pipe 44 as weremaintained'when both pumps were operating. 1

Referring particularly to Fi e 3, the system ure 1, with threeexceptions. In the first place, the pipe 22 and the pump 20 areeliminated so thatall oi the excess water moves through the pipe means2. In the second place, the stream in the pipe 66 is combined with thecondensate in the pipe 1.4 at a junction I00 before being hetank l5.,I'his combining of the two streams does "not modify the action takingplace in the subsequent portion of the equipment but serves to transferheat directly to the condensate. However, 'in this system, if the secondchamber 61 is maintained at atmospheric pressure, some heat condensateand the make-up water through the pipe I6 is not sumcient to reduce thetemperature of 'the stream in the pipe 66 tea value below 212 F; In thethird place, the embodiment in Figure 3 diflfers from Figure 1 in theuse of a different type of restricting nozzle 9. Instead of provides aconical discharge passage formed by conical plates I83 and I84 torelease the stream into the steam chamber and subdivide the. water intosmall droplets. Such a nozzle means, or any single-orifice dischargemeans, can be used in conjunction with Figure 1 without departing fromthe invention.

This application-is a continuation-in-part of my. copending application,entitled Steam generator," now Patent No. 2,154,683.

Various changes arid modifications can be made without departing fromthe spirit of the invention as defined in the appended claims.

I claim as my invention:

1. A method ot generating steam which includes the steps of: movingunder pressure along an elongated heating zone a stream of water inexcess of that required to meet'the steam demand while heating saidstream during flow therethrough to a steam-forming temperature;discharging this heated stream into a steam chamber and there'separatingsteam iromthe excess water and forming a body 01' said excess water.

. steam at said level; reducing the pressure on at least a portion ofsaid water thus withdrawn; adding to this water while at reducedpressure an amount of make-up water suflicient when vaporized to meetthe steam demand; and pumping said water-withdrawn from said steamchamber and said make-up water into the intake end of said elongatedheating zone to form said stream moving under pressure therethrough.

2. A method of generating steam which includes the steps of: movingunder pressure along an elongated heating zone a stream of water inexcess of that required to meet the steam"de mand while heating saidstream during flow ,therethrough to a steam-i'orming temperature,

discharging thisheated stream into a steam chamber and there separatingsteam from the excess water, and forming abody of said excess waterin-the lower end of said steam chamber; withdrawing steam from saidchamber to meet the steam demand; withdrawing water from said steamchamber at a given maximum level. as it is substantially the same asthat shown in Figlivered to the second chamber 6'l-provided by thelossesmay occur if the cooling action of thewhen vaporized to meet the steamdemand; and

pumping said water withdrawn from said steam chamber and said make-upwater into the intake end or said elongated heating zone toform saidstream moving under pressure therethrcugh.

3. A method of eneratlng steam which includes the steps of: oving underpressure along an elongated heating zone a stream of water in excess ofthat j'requlred to meet the steam de mand while heating said streamduring flow therethrough to a steam-forming temperature; dischargingthis heated stream into a steam chamber and there separating steam fromthe passage providing an entryportion disposed at a'.

position horizontally opposite the maximum desired water level any watertending to accumulate above said level while precluding the escape ofsteam at said l'evel'throughsaid'passage; re' turning this excess waterto the intake end'of said elongated heating zone under pressure; and

supplying anamount of make-up water to said heating zone to meet thesteam demand.

4. A method of generating steam [which in-- cludes the-steps of: movinga stream of water through an elongated heating zone and into a in saidsteam chamber and leave an excess of.

unvaporized water which separates from the steam in said steam chamberand tends to collect as a body in the lower end thereof: withdrawingsteam from said steam chamber ata rate suillcient to meet the steamdemand; withdrawing water from said steam chamber at two points;re-circulating the water withdrawn at onepoint to said elongated heatingzone; adding make-up water to the water withdrawn at said second pointin amount sufllcient to meet the steamfdemand; and returning theresulting make-up wa ter and water withdrawn from said steam chain'- berto said elongated heating zone. v

5. A method of generating steam which includes the stepsof: moving astream of water through an elongated heating zone and into asteamchamber at a rate in excess of the steam demand while applyingsufllcient heat to said' cient to meet the steam demand; withdrawingwater from said steam chamber at two points;

withdrawing water from one of said points at a predetermined rate andreturning'the same to said elongated heating zone; withdrawing water atthe other point so as to maintain the water level in said steam chambernot substantially higher'than a predetermined level; adding makeup waterto the water withdrawn at said second point in amount suflicient to meetthe steam demand; andreturning the resulting make-up water and waterwithdrawn from saidsteam chamber to said elongated heating zone.

6. A method as defined in claim 4 including the step of reducing thepressure on the water withdrawn at said second point to a value belowthe pressure in said steam chamber and adding said make-up water theretowhile at said lower pressure. v

7. A method as'defined in claim 4 including the step of controlling theheating of said stream in response to changes in the thermal conditionsof the stream near the end of said elongated heating zone to maintainthese thermal conditions substantially constant, and including the stepof stopping the withdrawal of water from said chamber from at least oneof said points, and consequently the return of this water to'saidpressure in said chamber, drops to a prereturning the condensate to asecond chamber; a

- elongated heating zone, when the pressure in said steam chamberrises'above a predetermined value and againstarting said withdrawal whenthedetermined lower-value. 1

'8. A method of generating steam which includesthe steps of: movinga's'tream or water through an elongated heating zone and. into .'a"steam chamber at a rate inexcess of the steam demand while applyingsufficient heat to said stream to cause steam to separate from the waterin "said steam chamber and leave an excess of}? unvaporized water whichseparates from the steam in said steam chamber and tends'to collect as abody in the lower 'end thereof; withdrawing steam from said steamchamber at a rate sufllcient to meet the steam demand; condensing atleast a Part of the steam 'thus withdrawn and withdrawing water fromsaid steam chamber at a desired maximum level as it reaches said leveland at such rate as to prevent a rise in the water level in said steamchamber above said level while precluding the escape of steam at saidlevel and conducting said water to said second chamber to obtain aheatexchange between the water thus withdrawn and said condensate;andwithdrawing ,water. from said second chamber and returning it to saidelongated heating zone;

9. A method of generating steam which in-' eludes the steps of; moving astream of water through an elongated heating zone and into a steamchamber at a'rate in excess or the steam demand while applyingsufllcient heat to said stream to cause steam to separate from th water;in said steam chamber and' leave an excess of unvaporized water whichseparates from the steam in said steam chamber and tends to collect as abody in the lower end thereof; withdrawing steam i'rom said steamchamberat a rate sufll- 40 cient tomee't the steam demand; condensing atleast a part of the steam thus withdrawn and returning the resultingcondensate to a second chamber while maintaining this second chamber atsubstantially atmospheric pressure; withdrawing excess water at a givenmaximum level from said steam chamber at a rate sufllcient to preventthe rise of said level above said maximum level and discharging saidwater into said second chamber while precluding the escape of steam atsaid-maximum level; adding make-up water to said second chamber; andperiodically withdrawing said condensate and make-up water from saidsecond chamber and returning same to said elongated heating zone underpressure.

10. A method of generating steam which includes the steps of: moving astream of waterthrough an elongated heating zone and into a steamchamber at a rate inexcess of the steam demand while applying sufficientheat to said stream to cause steam to separate from the water in saidsteam chamber and leave an excess of unvaporized water which separatesfrom the steam in said steam chamber and tends to collect as a bodyinthe lower end therof; withdrawing steam from saidsteam chamber at arate sumcient to meet the steam I. demand; condensing at least a part ofthe steam thus withdrawn and returning the resulting condensate to asecond. chamber; withdrawing water at a given maximum level fromsaid'steam chamber at a rate sufificient. to prevent the rise of'saidlevel above said max-' imum level while precluding the escape of steamatsaid level and conducting said water to said "her to saidelongate'dheating zone.

1 anew second" chamber suchamount as to substantially a constantamountof water therein; *and pumping water from said second cham- 11; Amethod of generating steam-which ineludes the steps of: moving a streamof water thorugh an elongated heating zone and into a steam chamber at arate in excess of the steam demand while applying sunlcient' heat tosaid stream to cause steam to separate from the water in said steamchamber and leave an excess of unvaporized water "which separates fromthe steam infisaid steamichambenrand-tends to collect as a body in thelower end thereof; withdrawing steam y from said steam chamber at a ratesufllcient to meet the steam'deman'd; condensing at least a part of thesteam thus withdrawn and returning. the resulting condensate to a secondchamber; withdrawing water at a given maximum level from said steamchamber at arate suiiicient' to prevent the rise of said level abovesaid maximum level while precluding the escape of steam at said leveland'moving said waterin heat-transferring=relationwith said condensate;and withdrawing water from saidsecond tank and forcing same. into saidelongated heating zone.

' 12. Amethod of generating steam, which includesthe steps of: movingunder pressure along an elongated heating zone a stream of water inexcess of that required to-meet the steam demand; heating said streamand expanding same as a Jet into-an upper'steam zone of a steam chamberin which the pressure is lower than in a portion of said elongatedheating zone, while controlling the heat applied to said heating zone tosuperheat the water therein tosuch an extent that release into saidsteam zone will flash a portion pf'thesuperheated water into steam andform a jet containing both water droplets and.

steam facilitate 'ebullition, said water droplets dropping to'the'lowerpart of said steamchamher. to forma body of water; withdrawing steamfrom said steam zone to meet the steam demand; determining the uppermostposition of the surface of said body-of water by withdrawing zone alongwith suillcient make-up water to meet the steam demand.

1113': A method of generating steam, which in- "cludes the-steps of::moving under pressure alon an elongated heating zone a stream of water;heating this water to such an extent that a portion but not all thereofis vaporized. while maintaining such velocity in saidelongated heatingzone'as' will prevent separation of the steam from thewater withconsequent steam pockets thereby forming a heated stream comprisingmixed steam and water; discharging thisheated stream intoa'njupper steamzone ot a steam chamber while restricting this discharge toform anexpandlng iet-insaid steam zone and comprising both small water dropletsand steam to facilitate 'ebullition, the water droplets dropping to thelower'partof chamber to form a body of water; determining the uppermostposition of (the 'surfaceof said body of water bywithdrawing-fromsaidsteam chflel at the'desired uppermost position ofsaid surface all excess water entering this chamber; and returning thisexcess waterto' s'aid elongated heating zone.

V14. In combination in a device for'generating steam walls defining anelongated heating zone;

swap m et providing an intake and a discharge for delivering a stream'of water thereto in amount 1 greater than that required to meet thesteam demand; heating means for said elongated heating zone; acontainenproviding a' mechan sm ig,

from said second chamber to said intake of said.

Dump means. 7

15. In'combination in a device for generating I steam: means providing aheating zone; a pump means for delivering a stream of water to saidheating zone at a rate in excess of that required to meet the steamdemand; a container providing a steam chamber; means for delivering aheated stream from said heating zone to ,said steam chamber; means forsupplying heat to said heatingzone in amount insuflicient to vaporizeall of the water supplied thereto but suflicient to maintain steam inthe upper end of said steam chamher, the excess water collecting as abody in .the lower end thereof a tank providing a second chamber; pipemeans communicating with said steam chamber and providing an entryportion disposed horizontally opposite the desired upper- 85 mostposition of the surface .of said body 'of water, said pip meanscommunicating with said second chamber whereby water may move from saidsteam chamber to said second chamber when said surfacehises: meansconnected in said 40 pipe means for allowing the ilow of water from saidsteam chamber to said second chamber while precluding the escape ofsteam through said pipe means; means for withdrawing steam from theupper end of said steam chamber; means for supplying make-up watertosaid second chamber; and means communicating between said secondchamber and said pump means for delivering water to said pump means forsubsequent circulation through said heating zone. 1 5o 16. Incombination ina device for generating steam: means providing a heatingzone; a pump means for delivering astream-of waterto said heating zoneat a rate in excess of that required to meet the steam demand; acontainer providing a steam chamber; means for delivering a heatedstream from said heating zone to said steam chamber; means for supp heatto said heating zone in amount insuilicient to vaporize all of watersupplied thereto but suiiicient to maintain to steam in the upper end.of said steam chamber, the excess water'collecting as a body in thelower end thereof; a tank providing a'second chamber;

pipe means communicating with" said steam chamber and providing an entryportion disposed horizontally opposite the desired uppermost positionofthe surface of said body of water, said pipe means communicating withsaid second chamber whereby water may move from said steam chamber tosaid second chamber when said surface rises; automatic means connectedinsaid'pipe means for controlling the flow of water through said pipemeans while precluding the escape of steam through said pipe means;means for withdrawing steam from the upper end of said ass-rises Y steamchamberandmovingsametoaloadactingtocondenseatleastaportionofthesteam;

- means for delivering the resulting condensate to said second chamber;and means communicating between said second chamber and said pump tainerproviding a steam chambercontaining steam in its upper endand a body ofwater in delivering a heated stream from said heating zone to said steamchamber; a pipe means communicating with said steam chamber andproviding an entry portion disposed horizontally opposite the desireduppermost position of the surface of said body of water, wherebywaterewill be withdrawnffrom said steam chamber when said surface risesto a position adjacent said entry portion; a steam trap communicatingwith said pipe means to prevent the passage of steam therethrough shouldsaid surface drop to a position below said entryportion; pump means fordelivering to said heating zone the water discharged through'said steamtrap; and means for tainer providing a steam chamber containing steam inits upper end and a body of water in its lower end; means forwithdrawing steam from the upper end of said steam chamber; means fordelivering a heated streamfrom said heating zone to said steam chamber;a pipe means-comits lower end; means for withdrawing steam from theupper end of said steam chamber; means for mun'icating with said steamchamber and providing an entry portion disposed horizontally oppositethe desired uppermost position of themface of said body of water wherebywater will be withdrawn from said steam chamber when said surface risesto a position adjacent said entry portion; a tank communicating withsaid pipe means to receive any water withdrawn therethrough from saidsteam chamber, said water collecting in said tank means forsupplyinglower end; means for withdrawing steam from the upper end ofsaid steam chamber; means for delivering a heated stream from saidheating zone to said steam chamber; a pipe means communicating with saidsteam chamber and providing an entry portion disposed horizontallyopposite the desired uppermost position of the surface of said body ofwater whereby water will.

be withdrawn from said steam chamber when said surface rises to aposition adjacent said entry portion; a tank communicating with saidpipe means to receive any water withdrawn therethrough from said steamchamber. said water collecting in said tank; a first pump forwithdrawing'water from said body of water in said steam chamber andreturning same to said heating zone; a second p'ump withdrawing waterfrom said tank and returning same to said heating zone; means forsupplying water to said tank;

and means for controlling the amount of water thus suppliedto said'tankto maintain the amount of water therein substantially constant.

20. A combination as defined in ciaim,18 including a steam trap in saidpipe means providing said entry portion for preventing flow of steamfrom said steam chamber to. said tank .while permitting discharge ofwater irom said steam chamber to said tank.

steam: a heater providing an elongated heating zone; a containerproviding a steam chamber ond chamber communicating with said last-'named means to receive any water withdrawn from said steam chamber;means for supplying water to said tank; means for controlling the amountof water thus supplied to said tank to maintain a substantially constantamount of water therein; pump means for withdrawing water from said tankand moving sam to said v heating zone; and pressure responsive meansassociated with said steam chamber for stopping said pump means when agiven pressure is attained in said steam chamber.

22. In combination in a device for producing steam: walls providing anelongated heating zone; pump means for elivering to one end of saidheating zone an amount of water in excess of that required to meet thesteam demand; heating means for progressively heating. the stream ofwater moving through said heating zone; means responsive to'the thermalconditions of the heated stream discharging from said heating zone'andoperatively connected to said heating means to automatically produce astream containing' both water and steam uniformly mixed, said elongatedheating zone being of such size asto maintain uniformly dispersed in thestream any steam formed therein while precluding separation of i thissteam and formation of steam pockets; 9. container providing a steamchamber containing steam in its upper end and a body of water in itslower end; conduit means for conducting the heated stream containingsteam and water to' the upper end of'said steam chamber;

a restricted nozzle means for releasing said stream from said conduitinto said steam chamber whereby an additional amount or water may iiashinto steam; means for withdrawing from said steam chamber all excesswater tending to raise the surface of s'aid body of water above apredetermined position; a tank containing a body of water; means fordelivering any water thus withdrawn from said steam chamber to said tankin heat-transferring relationship with the water.

heating zone at a rate in excess of that required 1 to meet the steamdemand; a container providing a steam chamber; means for delivering a 1021. In combination in a device for producing heated; stream from saidheating zone to said steam chamber; means for supplying heat to saidheating zone in amount insuflicient to vaporize all of the watersupplied thereto but suflicient to maintain steam in the upper end ofsaid steam chamber, the excess water collecting as a body in the lowerend thereof; a tank providing a second chamber; pipe means communicatingwith said steam chamber and providing an entry portion disposedhorizontally opposite the desired uppermost position of thesurface ofsaid body of water, said pipe means communicating witlr said secondchamber whereby water may move from said steam chamber to said secondchamber when said surface rises; and means for withdrawing steam fromthe upper end of said steam chamher, said pump means intaking both fromsaid steam chamber and from said second chamber for withdrawing waterfrom both chambers and delivering same to said heating zone.

24. A combination as defined in claim 23 including means for stoppingthe pumping action of said pump means when the pressure in said steamchamber rises above a predetermined point and for again, starting 'thepumping action of said pump means when said pressure drops to apredetermined point, and including ,means for controlling the amount ofheat delivered to said heating zone in response to variations in thermalconditions of the heated stream discharging therefrom to cut down theamount ofheat supplied when the pumping action of said pump means stops.

25. A method as defined in claim 4 including the step of controlling theheat of said stream in response to changes in the thermal conditionsofthe stream near the end of said elongated heating zone to maintain thesethermal conditions substantially constant.

26.-A method as defined in claim 4 including the step of stopping thewithdrawal of water from said chamber from at least one of said points,and consequently the return of this water to said elongated heatingzone, when the pressure in said steam chamber rises above apredetermined value and again starting said withdrawal when the pressurein said steam chamber drops to a predetermined lower value.

27. In combination ina device for producing.

steam: a heater providing, a heating zone; a container providing a steamchamber containing steam in its upper end and a body of water in itslower end; means for withdrawing steam from the upper end of said steamchamber; means for delivering a heated stream from said heating zone tosaid steam chamber; a tank; a pipe means communicating'with said steamchamber and "said tank and providing an entry portion disposedhorizontally opposite the desired uppermost position of the surface ofsaid body of water in said steam chamber, whereby water will bewithdrawn from saidsteam chamber and discharged into said tank when saidlevel rises to a level adjacent said entry portion; a steam trapcommunicating. with said pipe means to prevent the passage of steamtherethrough to said'tank should said level drop to a position belowsaidinsaid steam chamber for stopping said driving means when a givenpressure is attained in said steam chamber and again starting said drivemeansiupon a drop in pressure below said given pressure.

29. The combination as set forth in claim 18,

but including means for continuously driving said first pump, and meansresponsive to pressure in said steam chamber for effecting intermittentoperation of said second pump.

30. The combination as set forth in claim 18.

but including separate means for driving said first and second pumps;and "control means .for said pumps arranged to operate one of said pumpscontinuously, andto intermittently operatethe other of said pumps inaccordance with pressure changes-in said steam chamber.

31. The combination as set forth in claim 18,

32. The "combination as defined in claim 23 in cluding means forstopping the pumping action of said pump means when the pressure in saidsteam chamber rises above a predetermined point and for again startingthe pumping action of the pump means when said pressure drops to apredetermined point.

33. In combination, in a device for generating steam: walls defininganelongated heating zone;

pump means providing an intake and a discharge for delivering. a streamof water thereto in amount greater than that required to meet the steamdemand; heating means for said elongated heating zone; a containerproviding a steam chamber containing steam in its upper endand a body ofwater in its lower end; means 'for delivering the heated stream fromsaid elongated heating zone into said steam chamber for separation ofsteam and water, said means including a discharge means opening on theupper portion of said steam chamber whereby said stream discharges intoa steam zone ofsaid chamber at a position above said body of water, saiddischarge means further including a nozzle means acting to subdividesaid stream whereby the resulting water droplets move downward in saidsteam zone and provide a large surface area available for ebullition; atank defining a second chamher; a conduit ioridelivering water from saidcontainer to said second chamber; means for supplying make-up water tosaid second chamber; and means for conductingwater from said secondchamber to said intake of said pumping means.

34. In combination, in adevice for generating steam: means providing aheating zone; a pump means for delivering a stream of water to saidheating zone at a rate in excess of that required to meet the steamdemand; a container providing a steam chamber; means for delivering aheated stream fromsaid heating zone to said steam chamber; means forsupplying heat to' said heating zone in amount insumclent to vaporizeall of the water supplied thereto but sunlcient to maintain steam in theupper end of said steam chamber, the excess water collecting as a bodyin the lower end thereof; a tank providing a second chamber; pipe meanscommunicating withsaid steam chamber and providing an entry portiondisposed horizontally opposite the desired uppermost position of thesurface of said body of water, said pipe means communicating with saidsecond chamber whereby water may move from said steam chamber to saidsecond chamher when said surface rises; means for withdrawing steam fromthe upper end of said steam chamber; means for supplying make-up waterto said second chamber; means communicating between said -second chamberand said pump means for delivering water to said pump means forsubsequent circulation through said heating zone; means for stopping thepumping action of said pump means when the pressure in said steamchamber rises above a predetermined point and for again starting thepumping action of said pump means when said pressure drops to apredetermined point; and means for controlling the amount of heatdelivered to said heating zone in response to variations in thermalconditions oi the heated stream discharging therefrom to cut down theamount of heat supplied when the pumping action of said pump meansstops.

35. In combination, in a device for generating steam: means providing aheating zone; a pump means for delivering a stream of water to saidheating zone at a rate in excess of that required to meet the steamdemand; a container providing a steam chamber; means for delivering aheated stream from said heating zone to said steam chamber; means forsupplying heat to said heating zone in amount insuflicient to vaporizeall of the water supplied thereto but suflicient to maintain steam inthe upper end of said steam chamber the excess water collecting as abody in the lower-end thereof; a tank providing a second chamber; pipemeans communicating with said steam chamber and providing an entryportion disposed horizontally opposite the desired uppermost position ofthe surface of said body of water, said pipe means communicating withsaid second chamber whereby water may move from said steam chamber tosaid second chambe! when said surface rises; means for withdrawing steamfrom the upper end of said steam chamber; means'ior supplying make-upwater to said second chamber; means communicating between saidsecondchamber and said pump means for delivering water to said pumpmeans for subsequent circulation through said heating zone; means forstopping the pumping action of said pump means when the pressure in saidsteam chamber rises above a predetermined point and for again startingthe pumping action of said pump means when said pressure drops to apredetermined point.

WALTER B. KERRICK.

